botany department,archegoniate,sphagnum.sp

presentation about sphagnum species (botany department)

1. Systematic of nonflowering plant Chemistry and botany department

2. •INTRODUCTION •CLASSIFICATION •STRUCTURE •life cycle •REPRODUCTION CONTENT

3. Introduction to spagnum Sphagnum is a genus of approximately 380 species of mosses, commonly known as sphagnum moss, also bog moss and quacker moss. Accumulations of Sphagnum can store water, since both living and dead plants can hold large quantities of water inside their cells; plants may hold 16 to 26 times as much water as their dry weight, depending on the species. The empty cells help retain water in drier conditions.

4. Classification of sphagnum Kingdom:plantae Divisin : Bryophyta Class : Sphagnopsida Order : Sphagnales Family : sphagnaceae Genus : sphagnum

5. Structure of gametophyte of sphagnum The gametophyte (the dominant generation) is differentiated
into a stem carrying leaves.

In young leaves all the cells are alike, in most leaves , there
are two kinds of cells:

1)long narrow cells which remain alive and contain chloroplasts and they are green photosynthetic cells.

6. . (photosynthetic cells have regular reticulate arrangement with respect to one another)

2)large cells with spiral thickening in their wall which lost their potoplast and become hyaline.

(Hyaline cells play an important role in the absorption and retention of water)

The stem is internally differentiated into a central medulla followed by a cylinder of hadrome and a cortex.

The cortex at first is one cell in thickness but later it becomes
4-5 cells in thickness.

The cells of the cylinder ( hadrome ) are thickwalled and form
a supporting tissue.

7. LIFE CYCLE OF GAMETOPHYTE OF SPHAGNUM

8. Reproducti o n In Sphagnum ●Sphagnum is homothallic( monocious ) or
heterothallic( dioecious ) according to species.

●Antheridia gives sperm
&Archegonia gives egg cell.

●Fertilization takes place and the resulting zygote gives a
sporophyte which consists of a foot with haustoria , short seta and capsule.

●The amphithecium gives The jacket and the archespoium of the capsule. .

9. ●The endothecium gives the columella and in this respect is 3-4
cells in thickness.

●When the sporophyte matures the tissues of the gametophyte just beneath the foot develop into a leafless stalk known as the pseudopodium.